CA1299238C - Cathode coating dispersion for batteries - Google Patents
Cathode coating dispersion for batteriesInfo
- Publication number
- CA1299238C CA1299238C CA000556453A CA556453A CA1299238C CA 1299238 C CA1299238 C CA 1299238C CA 000556453 A CA000556453 A CA 000556453A CA 556453 A CA556453 A CA 556453A CA 1299238 C CA1299238 C CA 1299238C
- Authority
- CA
- Canada
- Prior art keywords
- coating dispersion
- cathode coating
- dispersion
- cathode
- dispersion according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000006185 dispersion Substances 0.000 title claims abstract description 54
- 238000000576 coating method Methods 0.000 title claims abstract description 23
- 239000011248 coating agent Substances 0.000 title claims abstract description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 19
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 16
- 239000010439 graphite Substances 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 230000001681 protective effect Effects 0.000 claims abstract description 13
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000011230 binding agent Substances 0.000 claims abstract description 10
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000006229 carbon black Substances 0.000 claims abstract description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000005977 Ethylene Substances 0.000 claims abstract description 6
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229920001577 copolymer Polymers 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- 239000004094 surface-active agent Substances 0.000 claims description 17
- 150000001732 carboxylic acid derivatives Chemical class 0.000 claims description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 3
- 230000009974 thixotropic effect Effects 0.000 claims description 3
- 229920002554 vinyl polymer Polymers 0.000 claims description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 2
- 238000010348 incorporation Methods 0.000 claims description 2
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 2
- 239000003513 alkali Substances 0.000 abstract description 3
- 239000012799 electrically-conductive coating Substances 0.000 abstract 1
- 239000000203 mixture Substances 0.000 description 8
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 7
- 239000004020 conductor Substances 0.000 description 7
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- -1 e.g. Substances 0.000 description 4
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000002518 antifoaming agent Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229920000151 polyglycol Polymers 0.000 description 2
- 239000010695 polyglycol Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 125000005599 alkyl carboxylate group Chemical group 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- ZSBRYDJXHOFQMW-UHFFFAOYSA-N chloroethene;ethene;ethenyl acetate Chemical group C=C.ClC=C.CC(=O)OC=C ZSBRYDJXHOFQMW-UHFFFAOYSA-N 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 239000005038 ethylene vinyl acetate Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000007970 homogeneous dispersion Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/10—Primary casings; Jackets or wrappings
- H01M50/116—Primary casings; Jackets or wrappings characterised by the material
- H01M50/124—Primary casings; Jackets or wrappings characterised by the material having a layered structure
- H01M50/1243—Primary casings; Jackets or wrappings characterised by the material having a layered structure characterised by the internal coating on the casing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Paints Or Removers (AREA)
- Primary Cells (AREA)
- Conductive Materials (AREA)
- Sealing Battery Cases Or Jackets (AREA)
- Cell Electrode Carriers And Collectors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A cathode coating dispersion containing graphite and/or carbon black is disclosed which is suitable for battery production, especially for forming a water-resistant and alkali-resistant and yet electrically conductive coating on the cathode surfaces. The protective film is applied as a homogeneous aqueous dispersion and contains a binder which is a copolymer of (a) vinyl acetate and ethylene, or (b) vinyl acetate and vinyl chloride, or (c) styrene and butadiene or (d) vinyl acetate, vinyl chloride and ethylene.
A cathode coating dispersion containing graphite and/or carbon black is disclosed which is suitable for battery production, especially for forming a water-resistant and alkali-resistant and yet electrically conductive coating on the cathode surfaces. The protective film is applied as a homogeneous aqueous dispersion and contains a binder which is a copolymer of (a) vinyl acetate and ethylene, or (b) vinyl acetate and vinyl chloride, or (c) styrene and butadiene or (d) vinyl acetate, vinyl chloride and ethylene.
Description
This invention relates to a graphite-containing cathode coating dispersion for batteries with improved storage and discharge properties, which is applied to the cathode holder and forms an electrically conductive protective film thereon.
From Japanese Published Patent Document No. 56-145503 alkali dry cells are known which exhibit improved self-discharge properties. The improvement is attained by an electrically conductive protective film made of polyvinyl isobutyl eth0r and a carbon-containing material, applied to the inside of the cathode container. The materials are applied with the help of an organlc solvent, e.g., xylene, and, after evaporation of the solvent, an electrically conductive film with rubberlike elasticity remains.
Japanese Published Patent Document No. 59-224054 (C.A. 102:175, Ollf) also describes an electrically c o n d u c t iv e c o m p o s i t io n o f g r ap h it e a n d polyvinylpyrrolidinone on the inner surface of a battery container. Ethanol is proposed as a solvent for the polyvinylpyrrolidinone and as a carrier for dispersing the graphite.
The drawback of these coatings i-~ the necessity of applying an organic solvent as the carrier of the components. However, in the manufacturing process for battery production, solvent vapors are undesirable and can lead to considerable breakdown by exhaust air filter damage or require a special explosion protection.
The use of known type conductive varnishes is also un~atisfactory, since the resultant films are not water-resistant.
The use of lattices has further drawbacks, since they are not resistant in the prevailing oxidative conditions or in alkaline medium.
An object of the invention is to provide a dispersion for the coating of cathode supports, which requires no organic solvent and leads to protective films 1~9~3~3 which are water resistant and resist oxidative attacks and alkaline media.
According to the invention, there is provided a cathode coating dispersion containing graphite or carbon black, which is applied as an aqueous dispersion and contains a binder which is a copolymer of (a) vinyl acetate and ethylene, or tb) vinyl acetate and vinyl chloride, or (c) styrene and butadiene, or (d) vinyl acetate, vinyl chloride and ethylene. The cathode coating dispersion forms an electrically conductive protective film on the cathode holder. The resultant batteries have improved storage and discharge properties.
Advantageously, a copolymer of styrene and butadiene is carboxylated and thus made cross-linkable by incorporation of an unsaturated carboxylic acid, preferably acrylic acid. Especially such styrene-butadiene copolymers are used which have a styrene content of more than 50 percent, preferably between 70 and 80 percent. Naturally, mixtures of the indicated binders can also be used.
The dispersions according to the invention advantageously behave pseudoplastically and thixotropically.
An essential component of the dispersion is water, which functions as the carrier of the solid portion.
The water portion of the ready-to-use dispersion is advantageously 40 to 95 percent by weight, preferably 50 to 80 percent by weight.
Graphite or carbon black, such as acetylene black, or mixtures thereof is used as the electrically conductive material.
Suitable graphites includes natural and synthetic graphites of high purity and high crystallinity. The ash content should be below 0.1 percent. Especially suitable are graphites which additionally exhibit a grain size of less than 6 microns and a BET surface of 12 m2/g or more.
The electrically conductive material is advantageously used in an amount of ~0 to 85 percent by weight, based on the dry mass of the dispersion (conductive material, surfactants, additives and polymer).
Preferably such portion amounts to 55 to 75 percent by weight. The ratio of conductive material to binder is also important, since the aim is high conductivlty and the latter depends to a large extent on the conductive material.
For the cathode coating dispersions accordlng to the invention the ratio of conductive material to binder i8 advantageously between 4:1 and 1:2, preferably between 3:1 and 1:1.
In addition, the dispersion advantageously contains a ~urfactant or a mixture of different surfactants. Suitably commercial products from the series of nonionogenic surfactants or fluorosurfactants are used as the surfactants. These surfactants have the function of making the graphite and/or carbon black wettable, of making possible the production of a homogeneous disper-qion and of avoiding inclusion of air in the dispersion and ultimately in the protective film.
It may be advantageous to use mixtures of two or more surfactants to achieve such objects in an optimum manner.
The amount of surfactant or surfactants used generally amounts to from 0.5 to 5 percent by weight, based on the dry mass of the dispersion. Greater amountY
of surfactants are not advisable since otherwise the adhesion of the protective film to the surface to be treated may be reduced.
It may also be advantageous to provide other additives, such as, antifoaming agents, in the formulations.
The dispersion according to the invention is produced so that the conductive component, together with the surfactant or surfactants and optionally other additives, are mixed with water to form a predispersion.
i2~9;238 Advantageously the procedure in this ca~e is such that, first the surfactant or surfactant mixture, optionally with other additives, is placed in water and thereafter the conductive material is added. Then the binder, S usually prepared as approximately 50 percent aqueous dispersion, is added to this predispersion, and by intensive mixing is further processed to form the ready-to-use homogeneous dispersion.
The cathode coating dispersion according to the invention advantageously exhibits a pseudoplasticity and thixotropic behaviour. Its viscosity is advantageously in the range of 0.05 to 1.2 Pa.s ~20C), preferably from 0.06 to 1 Pa.s ~20C).
Application of the dispersion can take place in a manner known in the art, for example by immersion, pouring, painting or spraying. The water can be removed by allowing the dispersion to dry, optionally accompanied by warming or by application of a vacuum.
The amount to be applied is advantageously selected so that the film thickness of the protective film after evaporation of the water is from 5 to 200 microns and preferably from 20 to 100 microns. Thus, a film is formed which is uniform both in itself and in film thickness~
The cathode coating dispersion accordin~ to the invention i8 suitable for treatment of cathode surfaces of primary and secondary batteries. A preferred field of use is the treatment of the inside surface of battery cans.
In particular, alkali dry cells are produced by preforming a steel can and nickel-plating at least the inside thereof. Molded rings made from the cathode material, containing a mixture known in the art of manganese dioxide, graphite and potassium hydroxide are introduced into this can and fitted tightly on the inside can surface. To improve the electrical contact between the can and the rings of cathode material and especially to prevent corrosion of both the nickel layer and the can itself, the can i8 treated on the inside with a dispersion ~2~9~
according to the invention. A uniform layer thickness is attained by using the thixotropic and pseudoplastic properties of the dispersion. After removal of the water, a mechanically and chemically resistant, electrolyte-insoluble protective film remains. Moreover, as a result of the high content of pure and highly crystalline graphite, of the above-mentioned type, an optimal conductivity is guaranteed.
The following Examples illustrate the invention.
Example 1 19.6 g of graphite (99.~ percent C, less than 6 microns) KS 6 LON2A
0.7 g of surfactant (alkylacryl polyglycol ether) and 0.05 g of wetting agent ~fluorinated alkyl carboxylate) were mixed with 64.5 g of water to form a predispersion, and then processed with 19.9 g of a binder in the form of a 50 percent aqueous vinyl acetate-vinyl chloride-ethylene copolymer dispersion, so as to form a ready-to-use dispersion.
The dispersion was manually applied in a layer thickness of about 60 microns to nickel-plated sheets.
After a drying time of 5 hours at room temperature and 0.5 hour at 110C, the scratch hardness according to ISO 1518 for assessing the adhesion was determined. A value of about 2 N was measured, which corresponds to an average adhesion.
In a further test, steel cans, nickel-plated on the inside, were coated with the above dispersion and dried for 5 hours at room temperature and 0.5 hour at 110C.
Then cathode rings, consisting of manganese (IV) trade-mark 1~99~'23~
5a oxide/graphite and potassium hydroxide solution, were introduced into the cans. The samples were stored for four weeks in closed containers. For comparison, steel sheets, nickel-plated on the inside, were treated in the same manner without protective dispersion. After four ;Z3~
weeks of storage, it was possible definitely to establish by the degree of discoloration of the nickel layer that the uncoated can corroded, but the coated can did not.
Example 2 280 g of graphite KS 6 LONZA, 7 g of surfac~ant (aromatic polyglycol ether), and 0.6 g of antifoaming agent (fatty acid ester, hydrocarbon mixture) were mixed with 39~.4 g of water to form a predispersion, and then processed with 240 g of a binder in the form of a 50 percent aqueous vinyl chloride-ethylene-vinyl acetate copolymer dispersion, so as to form a ready-to-use dispersion.
The viscosity of the dispersion was 0.0~5 Pa.s, and the degree of adhesion of a 60-micron layer on a nickel-plated sheet was 10 N ~according to ISO 1518).
Furthermore, the change of the contact resistance cathode-nickel-plated can or nickel-plated sheet during storage at increased temperature was determined.
The following table shows the resistance increase of the boundary layer of the cathode (manganese (IV) oxide/graphite/potassium hydroxide)/nickel-plated steel can during storage at 60C, provided in one case with a contact layer according to this Example of 60 microns and in another case without a contact layer:
Resistance (ohm) Day O Day 5Day 10 with contact 0.010.05 0.1 (example of layer invention) without contact 0.05 0.3 2.4 (comparison) layer After the test piece was taken apart, the contact dispersion showed the same good adhesion as immediately after the coating and mixing of the samples.
3~
Example 3 Following the ~ame procedure as described in ~xample 1, 180 g of graphite KS 6 LONZA, 20 g of acetylene black, 5 ~ of surfactant, 3 g of antifoaming agent, 675 g of water and 240 g of an aqueous 50 percent carboxylated styrene-butadiene copolymer dispersion (about 70 percent styrene) were processed to form a dispersion.
The viscosity of the dispersion was 0.96 Pa.s, and the adhesion of a 60-micron layer to a nickel-plated sheet was 6 N (according to ISO 1518).
Study of the contact resistance, as described in Example 2, provided the following values:
Resistance (ohm) Day O Day 5 Day 10 with contact 0.01 0.15 0.3 (example of layer invention) without contact 0.05 0-3 2.4 (comparison) layer
From Japanese Published Patent Document No. 56-145503 alkali dry cells are known which exhibit improved self-discharge properties. The improvement is attained by an electrically conductive protective film made of polyvinyl isobutyl eth0r and a carbon-containing material, applied to the inside of the cathode container. The materials are applied with the help of an organlc solvent, e.g., xylene, and, after evaporation of the solvent, an electrically conductive film with rubberlike elasticity remains.
Japanese Published Patent Document No. 59-224054 (C.A. 102:175, Ollf) also describes an electrically c o n d u c t iv e c o m p o s i t io n o f g r ap h it e a n d polyvinylpyrrolidinone on the inner surface of a battery container. Ethanol is proposed as a solvent for the polyvinylpyrrolidinone and as a carrier for dispersing the graphite.
The drawback of these coatings i-~ the necessity of applying an organic solvent as the carrier of the components. However, in the manufacturing process for battery production, solvent vapors are undesirable and can lead to considerable breakdown by exhaust air filter damage or require a special explosion protection.
The use of known type conductive varnishes is also un~atisfactory, since the resultant films are not water-resistant.
The use of lattices has further drawbacks, since they are not resistant in the prevailing oxidative conditions or in alkaline medium.
An object of the invention is to provide a dispersion for the coating of cathode supports, which requires no organic solvent and leads to protective films 1~9~3~3 which are water resistant and resist oxidative attacks and alkaline media.
According to the invention, there is provided a cathode coating dispersion containing graphite or carbon black, which is applied as an aqueous dispersion and contains a binder which is a copolymer of (a) vinyl acetate and ethylene, or tb) vinyl acetate and vinyl chloride, or (c) styrene and butadiene, or (d) vinyl acetate, vinyl chloride and ethylene. The cathode coating dispersion forms an electrically conductive protective film on the cathode holder. The resultant batteries have improved storage and discharge properties.
Advantageously, a copolymer of styrene and butadiene is carboxylated and thus made cross-linkable by incorporation of an unsaturated carboxylic acid, preferably acrylic acid. Especially such styrene-butadiene copolymers are used which have a styrene content of more than 50 percent, preferably between 70 and 80 percent. Naturally, mixtures of the indicated binders can also be used.
The dispersions according to the invention advantageously behave pseudoplastically and thixotropically.
An essential component of the dispersion is water, which functions as the carrier of the solid portion.
The water portion of the ready-to-use dispersion is advantageously 40 to 95 percent by weight, preferably 50 to 80 percent by weight.
Graphite or carbon black, such as acetylene black, or mixtures thereof is used as the electrically conductive material.
Suitable graphites includes natural and synthetic graphites of high purity and high crystallinity. The ash content should be below 0.1 percent. Especially suitable are graphites which additionally exhibit a grain size of less than 6 microns and a BET surface of 12 m2/g or more.
The electrically conductive material is advantageously used in an amount of ~0 to 85 percent by weight, based on the dry mass of the dispersion (conductive material, surfactants, additives and polymer).
Preferably such portion amounts to 55 to 75 percent by weight. The ratio of conductive material to binder is also important, since the aim is high conductivlty and the latter depends to a large extent on the conductive material.
For the cathode coating dispersions accordlng to the invention the ratio of conductive material to binder i8 advantageously between 4:1 and 1:2, preferably between 3:1 and 1:1.
In addition, the dispersion advantageously contains a ~urfactant or a mixture of different surfactants. Suitably commercial products from the series of nonionogenic surfactants or fluorosurfactants are used as the surfactants. These surfactants have the function of making the graphite and/or carbon black wettable, of making possible the production of a homogeneous disper-qion and of avoiding inclusion of air in the dispersion and ultimately in the protective film.
It may be advantageous to use mixtures of two or more surfactants to achieve such objects in an optimum manner.
The amount of surfactant or surfactants used generally amounts to from 0.5 to 5 percent by weight, based on the dry mass of the dispersion. Greater amountY
of surfactants are not advisable since otherwise the adhesion of the protective film to the surface to be treated may be reduced.
It may also be advantageous to provide other additives, such as, antifoaming agents, in the formulations.
The dispersion according to the invention is produced so that the conductive component, together with the surfactant or surfactants and optionally other additives, are mixed with water to form a predispersion.
i2~9;238 Advantageously the procedure in this ca~e is such that, first the surfactant or surfactant mixture, optionally with other additives, is placed in water and thereafter the conductive material is added. Then the binder, S usually prepared as approximately 50 percent aqueous dispersion, is added to this predispersion, and by intensive mixing is further processed to form the ready-to-use homogeneous dispersion.
The cathode coating dispersion according to the invention advantageously exhibits a pseudoplasticity and thixotropic behaviour. Its viscosity is advantageously in the range of 0.05 to 1.2 Pa.s ~20C), preferably from 0.06 to 1 Pa.s ~20C).
Application of the dispersion can take place in a manner known in the art, for example by immersion, pouring, painting or spraying. The water can be removed by allowing the dispersion to dry, optionally accompanied by warming or by application of a vacuum.
The amount to be applied is advantageously selected so that the film thickness of the protective film after evaporation of the water is from 5 to 200 microns and preferably from 20 to 100 microns. Thus, a film is formed which is uniform both in itself and in film thickness~
The cathode coating dispersion accordin~ to the invention i8 suitable for treatment of cathode surfaces of primary and secondary batteries. A preferred field of use is the treatment of the inside surface of battery cans.
In particular, alkali dry cells are produced by preforming a steel can and nickel-plating at least the inside thereof. Molded rings made from the cathode material, containing a mixture known in the art of manganese dioxide, graphite and potassium hydroxide are introduced into this can and fitted tightly on the inside can surface. To improve the electrical contact between the can and the rings of cathode material and especially to prevent corrosion of both the nickel layer and the can itself, the can i8 treated on the inside with a dispersion ~2~9~
according to the invention. A uniform layer thickness is attained by using the thixotropic and pseudoplastic properties of the dispersion. After removal of the water, a mechanically and chemically resistant, electrolyte-insoluble protective film remains. Moreover, as a result of the high content of pure and highly crystalline graphite, of the above-mentioned type, an optimal conductivity is guaranteed.
The following Examples illustrate the invention.
Example 1 19.6 g of graphite (99.~ percent C, less than 6 microns) KS 6 LON2A
0.7 g of surfactant (alkylacryl polyglycol ether) and 0.05 g of wetting agent ~fluorinated alkyl carboxylate) were mixed with 64.5 g of water to form a predispersion, and then processed with 19.9 g of a binder in the form of a 50 percent aqueous vinyl acetate-vinyl chloride-ethylene copolymer dispersion, so as to form a ready-to-use dispersion.
The dispersion was manually applied in a layer thickness of about 60 microns to nickel-plated sheets.
After a drying time of 5 hours at room temperature and 0.5 hour at 110C, the scratch hardness according to ISO 1518 for assessing the adhesion was determined. A value of about 2 N was measured, which corresponds to an average adhesion.
In a further test, steel cans, nickel-plated on the inside, were coated with the above dispersion and dried for 5 hours at room temperature and 0.5 hour at 110C.
Then cathode rings, consisting of manganese (IV) trade-mark 1~99~'23~
5a oxide/graphite and potassium hydroxide solution, were introduced into the cans. The samples were stored for four weeks in closed containers. For comparison, steel sheets, nickel-plated on the inside, were treated in the same manner without protective dispersion. After four ;Z3~
weeks of storage, it was possible definitely to establish by the degree of discoloration of the nickel layer that the uncoated can corroded, but the coated can did not.
Example 2 280 g of graphite KS 6 LONZA, 7 g of surfac~ant (aromatic polyglycol ether), and 0.6 g of antifoaming agent (fatty acid ester, hydrocarbon mixture) were mixed with 39~.4 g of water to form a predispersion, and then processed with 240 g of a binder in the form of a 50 percent aqueous vinyl chloride-ethylene-vinyl acetate copolymer dispersion, so as to form a ready-to-use dispersion.
The viscosity of the dispersion was 0.0~5 Pa.s, and the degree of adhesion of a 60-micron layer on a nickel-plated sheet was 10 N ~according to ISO 1518).
Furthermore, the change of the contact resistance cathode-nickel-plated can or nickel-plated sheet during storage at increased temperature was determined.
The following table shows the resistance increase of the boundary layer of the cathode (manganese (IV) oxide/graphite/potassium hydroxide)/nickel-plated steel can during storage at 60C, provided in one case with a contact layer according to this Example of 60 microns and in another case without a contact layer:
Resistance (ohm) Day O Day 5Day 10 with contact 0.010.05 0.1 (example of layer invention) without contact 0.05 0.3 2.4 (comparison) layer After the test piece was taken apart, the contact dispersion showed the same good adhesion as immediately after the coating and mixing of the samples.
3~
Example 3 Following the ~ame procedure as described in ~xample 1, 180 g of graphite KS 6 LONZA, 20 g of acetylene black, 5 ~ of surfactant, 3 g of antifoaming agent, 675 g of water and 240 g of an aqueous 50 percent carboxylated styrene-butadiene copolymer dispersion (about 70 percent styrene) were processed to form a dispersion.
The viscosity of the dispersion was 0.96 Pa.s, and the adhesion of a 60-micron layer to a nickel-plated sheet was 6 N (according to ISO 1518).
Study of the contact resistance, as described in Example 2, provided the following values:
Resistance (ohm) Day O Day 5 Day 10 with contact 0.01 0.15 0.3 (example of layer invention) without contact 0.05 0-3 2.4 (comparison) layer
Claims (11)
1. A cathode coating dispersion containing graphite or carbon black for the production of a battery with improved storage and discharge properties, which coating dispersion forms an electrically conductive protective film on the cathode holder, the protective film being applied as a homogeneous aqueous dispersion and containing a binder which is a copolymer of (a) vinyl acetate and ethylene, or (b) vinyl acetate and vinyl choride, or (c) styrene and butadiene or (d) vinyl acetate, vinyl chloride and ethylene.
2. A cathode coating dispersion according to claim 1, wherein the dispersion has a water content between 40 and 95 percent by weight.
3. A cathode coating dispersion according to claim 1, wherein the ratio of graphite and/or carbon black to binder is between 4:1 to 1:2.
4. A cathode coating dispersion according to claim 3, wherein the graphite or carbon black content of the dry mass is between 40 and 85 percent.
5. A cathode coating dispersion according to claim 2, 3 or 4, wherein the dispersion additionally contains a surfactant or several surfactants in an amount of from 0.5 to 5 percent by weight based on the dry mass of the dispersion.
6. A cathode coating dispersion according to claim 1, 2 or 3, wherein the dispersion shows a psuedoplastic and thixotropic behaviour.
7. A cathode coating dispersion according to claim 1, 2 or 3, wherein the dispersion has a viscosity of 0.05 to 1.2 Pa.s measured at 20°C.
8. A cathode coating dispersion according to claim 1, wherein the copolymer of styrene and butadiene is carboxylated by incorporation of an unsaturated carboxylic acid.
9. A cathode coating dispersion according to claim 8, wherein the unsaturated carboxylic acid is acrylic acid.
10. A cathode coating dispersion according to claim 8 or 9, wherein a carboxylated styrene-butadiene copolymer with a styrene content of more than 50 percent is used.
11. A battery or the cathode surfaces of a battery, containing an electrically conductive protective film having a thickness of from 5 to 200 microns thick and deposited from a cathode coating dispersion as defined in claim 1, 2 or 3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH12587 | 1987-01-15 | ||
| CH125/87 | 1987-01-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1299238C true CA1299238C (en) | 1992-04-21 |
Family
ID=4179825
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000556453A Expired - Fee Related CA1299238C (en) | 1987-01-15 | 1988-01-13 | Cathode coating dispersion for batteries |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US4810600A (en) |
| EP (1) | EP0275883B1 (en) |
| JP (1) | JP2667983B2 (en) |
| CN (1) | CN1012313B (en) |
| AT (1) | ATE79694T1 (en) |
| AU (1) | AU594280B2 (en) |
| BR (1) | BR8800121A (en) |
| CA (1) | CA1299238C (en) |
| DE (1) | DE3873781D1 (en) |
| DK (1) | DK172467B1 (en) |
| ES (1) | ES2033937T3 (en) |
| MX (1) | MX172098B (en) |
Families Citing this family (28)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3012240B2 (en) * | 1987-09-25 | 2000-02-21 | 東洋紡績株式会社 | Manufacturing method of polarizable electrode material |
| US5234627A (en) * | 1991-12-11 | 1993-08-10 | Dap, Inc. | Stability conductive emulsions |
| US5382196A (en) * | 1992-06-15 | 1995-01-17 | Lodrick; Lester B. | Personal cue chalk holder |
| US5494610A (en) * | 1992-06-29 | 1996-02-27 | Lovell; Walter C. | Apparatus and method for providing medium temperature conductive-resistant articles |
| DE69408195T2 (en) * | 1993-04-26 | 1998-11-05 | Gencorp Inc | Conductive molded coatings |
| US5506074A (en) * | 1993-09-30 | 1996-04-09 | Sanyo Electric Co. Ltd. | Metal hydride electrode and nickel-hydrogen alkaline storage cell |
| US5543249A (en) * | 1995-03-01 | 1996-08-06 | Wilson Greatbatch Ltd. | Aqueous blended electrode material for use in electrochemical cells and method of manufacture |
| US20030090021A1 (en) * | 2000-02-25 | 2003-05-15 | Mitsubishi Denki Kabushiki Kaisha | Electrode, method of fabricating thereof, and battery using thereof |
| US6572790B2 (en) | 2001-01-09 | 2003-06-03 | National Starch And Chemical Investment Holding Corporation | Cathode coating dispersion |
| US20030008209A1 (en) * | 2001-06-22 | 2003-01-09 | Marufur Rahim | Cathode coating dispersion |
| JP4049321B2 (en) * | 2001-11-21 | 2008-02-20 | 日立粉末冶金株式会社 | Fuel cell separator paint |
| US7261963B2 (en) * | 2002-11-12 | 2007-08-28 | General Motors Corporation | Corrosion resistant, electrically and thermally conductive coating for multiple applications |
| KR100578970B1 (en) | 2004-08-25 | 2006-05-12 | 삼성에스디아이 주식회사 | Electrode for fuel cell and fuel cell comprising same |
| DE102005043054A1 (en) * | 2005-09-09 | 2007-03-15 | Future Carbon Gmbh | Dispersion and process for its preparation |
| JPWO2008029502A1 (en) * | 2006-08-29 | 2010-01-21 | ユニチカ株式会社 | Electrode forming binder, electrode forming slurry using the binder, electrode using the slurry, secondary battery using the electrode, capacitor using the electrode |
| KR101670912B1 (en) * | 2008-12-11 | 2016-10-31 | 푸투레 카르본 게엠베하 | Conductive preparation and method for the production thereof |
| US20110027638A1 (en) * | 2009-07-29 | 2011-02-03 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Fluid-surfaced electrode |
| US8460814B2 (en) * | 2009-07-29 | 2013-06-11 | The Invention Science Fund I, Llc | Fluid-surfaced electrode |
| US8889312B2 (en) * | 2009-07-29 | 2014-11-18 | The Invention Science Fund I, Llc | Instrumented fluid-surfaced electrode |
| US10074879B2 (en) * | 2009-07-29 | 2018-09-11 | Deep Science, Llc | Instrumented fluid-surfaced electrode |
| US20110027629A1 (en) * | 2009-07-29 | 2011-02-03 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | Instrumented fluid-surfaced electrode |
| US8968903B2 (en) * | 2009-07-29 | 2015-03-03 | The Invention Science Fund I, Llc | Fluid-surfaced electrode |
| US8865361B2 (en) * | 2009-07-29 | 2014-10-21 | The Invention Science Fund I, Llc | Instrumented fluid-surfaced electrode |
| CN102484246A (en) | 2009-08-07 | 2012-05-30 | 鲍尔热尼系统公司 | Carbon fiber zinc negative electrode |
| FR2977364B1 (en) * | 2011-07-01 | 2015-02-06 | Hutchinson | CURRENT COLLECTOR AND METHOD FOR MANUFACTURING THE SAME |
| KR20210054023A (en) * | 2013-05-17 | 2021-05-12 | 밀텍 코포레이션 | Actinic and electron beam radiation curable water based electrode binders and electrodes incorporating same |
| US10168436B2 (en) * | 2016-05-10 | 2019-01-01 | International Business Machines Corporation | Water soluble low alpha particle emission electrically-conductive coating |
| JP6683028B2 (en) * | 2016-06-20 | 2020-04-15 | 東洋インキＳｃホールディングス株式会社 | Conductive composition, current collector with underlayer for power storage device, electrode for power storage device, and power storage device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2594047A (en) * | 1946-03-22 | 1952-04-22 | Olin Ind Inc | Cathode |
| IE34233B1 (en) * | 1969-04-18 | 1975-03-19 | Colour & Varnish Manufactures | Improvements in or relating to paint compositions |
| US3698953A (en) * | 1971-05-27 | 1972-10-17 | Elca Battery Co | Galvanic cell |
| DE2354023C3 (en) * | 1973-10-27 | 1978-08-31 | Varta Batterie Ag, 3000 Hannover | Method of manufacturing a positive electrode for primary elements with alkaline electrolyte |
| DE2645729C3 (en) * | 1976-10-09 | 1980-09-11 | Reuter Technologie Gmbh, 2844 Lemfoerde | Electrically conductive plastic compounds |
| US4125685A (en) * | 1977-06-30 | 1978-11-14 | Polaroid Corporation | Electrical cells and batteries and methods of making the same |
| JPS6041829B2 (en) * | 1979-01-06 | 1985-09-19 | 株式会社日立製作所 | Manufacturing method of positive electrode for non-aqueous electrolyte battery |
| US4351815A (en) * | 1979-06-11 | 1982-09-28 | Columbian Chemicals Company | Battery carbon black |
| JPS57177047A (en) * | 1981-04-22 | 1982-10-30 | Tokuyama Sekisui Kogyo Kk | Electrically conductive resin composition and video disc record |
| US4656105A (en) * | 1983-08-30 | 1987-04-07 | Mitsuit Toatsu Chemicals, Inc. | Iodine cell |
| US4687598A (en) * | 1983-11-07 | 1987-08-18 | The United States Of America As Represented By The United States Department Of Energy | Electrode-active material for electrochemical batteries and method of preparation |
| US4702860A (en) * | 1984-06-15 | 1987-10-27 | Nauchno-Issledovatelsky Institut Kabelnoi Promyshlennosti Po "Sredazkabel" | Current-conducting composition |
| IL76085A0 (en) * | 1984-08-21 | 1985-12-31 | Ray O Vac Corp | Alkaline primary battery containing coated current collector |
| GB8523906D0 (en) * | 1985-09-27 | 1985-10-30 | Ever Ready Ltd | Sheet electrode for electrochemicals cells |
-
1988
- 1988-01-08 AT AT88100186T patent/ATE79694T1/en not_active IP Right Cessation
- 1988-01-08 EP EP88100186A patent/EP0275883B1/en not_active Expired - Lifetime
- 1988-01-08 DE DE8888100186T patent/DE3873781D1/en not_active Expired - Fee Related
- 1988-01-08 CN CN88100116A patent/CN1012313B/en not_active Expired
- 1988-01-08 ES ES198888100186T patent/ES2033937T3/en not_active Expired - Lifetime
- 1988-01-13 JP JP63005659A patent/JP2667983B2/en not_active Expired - Lifetime
- 1988-01-13 CA CA000556453A patent/CA1299238C/en not_active Expired - Fee Related
- 1988-01-14 BR BR8800121A patent/BR8800121A/en not_active IP Right Cessation
- 1988-01-14 AU AU10282/88A patent/AU594280B2/en not_active Ceased
- 1988-01-14 US US07/143,743 patent/US4810600A/en not_active Expired - Lifetime
- 1988-01-14 MX MX010108A patent/MX172098B/en unknown
- 1988-01-14 DK DK198800156A patent/DK172467B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0275883B1 (en) | 1992-08-19 |
| DE3873781D1 (en) | 1992-09-24 |
| EP0275883A3 (en) | 1990-04-04 |
| ATE79694T1 (en) | 1992-09-15 |
| DK15688D0 (en) | 1988-01-14 |
| DK15688A (en) | 1988-07-16 |
| AU1028288A (en) | 1988-07-21 |
| BR8800121A (en) | 1988-08-23 |
| CN88100116A (en) | 1988-07-27 |
| US4810600A (en) | 1989-03-07 |
| EP0275883A2 (en) | 1988-07-27 |
| CN1012313B (en) | 1991-04-03 |
| MX172098B (en) | 1993-12-03 |
| DK172467B1 (en) | 1998-09-07 |
| AU594280B2 (en) | 1990-03-01 |
| ES2033937T3 (en) | 1993-04-01 |
| JPS63175336A (en) | 1988-07-19 |
| JP2667983B2 (en) | 1997-10-27 |
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